Conveyor system for planar objects

ABSTRACT

A conveyor system for reducing the speed of double-piece cut banks being fed to a stacker is provided. Cut-blanks are fed in pairs with the spacing between the blanks of the pair being small and the spacing between the pairs of objects being large along a first conveyor towards a detecting device which detects the leading edge of the blanks. A delivery member consisting of two sandwiching rollers is variably driven in accordance with signals given by the detecting device so as to deliver from the first conveyor the first blank of each pair at a first higher speed and the second blank of each pair at a second lower speed. Blanks are thereby delivered to a second slower conveyor which may be as low as V1=2l/LV2 wherein V2 is the speed of the first conveyor, l is the length of each blank, and L is the distance between the leading edge of a first pair of blanks to the leading edge of a second pair. Blanks are thereby fed slowly to a stacker so as to not damage the blanks, and are also fed in a evenly spaced, non-overlapping, manner.

FIELD OF THE ART

The present invention relates to a conveyor system for carrying planarobjects by way of a conveyor belt and the like.

BACKGROUND OF THE INVENTION

Corrugated cardboard boxes have been designed with a variety of sizes,shapes and in a variety of multicolor printings these days, and incoping with such designs, there have been presented a variety offunctions of the machine for manufacturing the corrugated cardboardboxes, accordingly. Now, referring to the conventional construction ofthe corrugated cardboard box manufacturing machine with reference toFIGS. 1 through 4, there are shown provided a blank board supply station1, a first printing machine 2, a second printing machine 3, printingcylinders 4, a transfer conveyor 5, a rotary die cutting station 6, aanvil cylinder 7, a die-cut cylinder 8, a die element 9, a boarddelivery conveyor (a scrap conveyor; a conveyor for a planar object) 10,a sheet of corrugated board 11, a die board 11' (through thesingle-cutting process), a died board 11" (through the double-cuttingprocess), a stacker-conveyor 12, a counter-stacker 13, a board stopper14, a spacing 16, a lifter 17, and a counting photoelectric tube 18,wherein a sheet of corrugated cardboard 11 is fed for printing by theboard supply station 1 with such a rate of delivery of a sheet persingle rotation of the printing cylinders 4 in the printing machines 2,3, thereafter is delivered outwardly by the transfer conveyor 5 forhaving the printing ink put in the surface of a cardboard 11 dried up,and then is died to a shape of cardboard box by way of the rotary diecutter 6. The die element 9 comprises a cutting knife edge or the likeimplanted around the circumferential surface of a curved veneer board ofa specified thickness, which is to be mounted onto the die-cut cylinder8 by using bolts, and is adapted to cut and die a sheet of cardboard 11to be fed from the foregoing step into the nip with the anvil cylinder7, which is wrapped with a layer of urethane rubber or the like formaking the cutting easier and preventing the wear of cutting edge, witha predetermined timing of cuting and dieing. The delivery conveyor(scrap conveyor) 10 is formed by a plurality of such carrier members asV-shaped belts or ropes having a circular section in an attempt topromote the dropping of chippings and cuttings from the product at thearea where there is provided a specific means such as an air blower or avibrator, and is constructed in a duplex structure for carrying the diedboard 11' in a sandwiched relationship over to a stacker-conveyor 12.There is provided a suction equipment in the stacker-conveyor 12, whichis adapted to attract by sucking and deliver the died cardboard 11' at aslow speed in the attempt to reduce a impace shock of the board againstthe cardboard stopper 14 provided in the counter-stacker 13 when hit,thus obviating a possibility of damages and/or irregular stacking of thecardboards from occurring when stacked upon the lifter 17. Also, thecardboard stopper 14 is designed shiftable back and forth by way of ahydraulic cylinder or the like in accordance with a given width of thedied board 11' as schematically shown in FIGS. 1 and 2.

The cardboard box manufacturing machine is of the type that a sheet ofcardboard 11 may be set either for one-piece cutting or for longitudinaldouble-piece cutting according to the size of a box to be died by usingthe die element 9 of the rotary die cutter 6. FIG. 3(III) shows the caseof the single-piece cutting process, FIG. 4(III) shows the longitudinaldouble-piece cutting, and FIG. 4(IV) shows the four-piece cuttingprocess (double-cuttings in the transversal and longitudinal ways makingfour pieces of boards), respectively. The die element 9 is to be set inthe circumferential surface of the die cut cylinder 8, with asingle-piece or double-piece cutting knife element implanted in workingposition in accordance with the size of a product box to bemanufactured, and with a spacing 16. This spacing 16 is provided for thereduction of conveying speed in consideration of a too great shock to begiven to the died cardboard 11' when hit against the cardboard stopper14, which is taken in the following manner; when a series of diedcardboards 11' after being died by the die cut cylinder 8 are stackedupon the lifter 17 by using the stacker-conveyor 12, as the carryingspeed of the stacker-conveyor 12 will, when the single-piece cutting isconducted (FIG. 3(III)), bring a too large shock on the died sheet 11'when hit against the cardboard stopper 14, if V₁ ÷V₂ (thecircumferential speed of the die cut cylinder 8 and the carrying speedof the delivery conveyor 10 are V₂, and the carrying speed of thestacker-conveyor 12 is V₁, as shown in FIG. 3(I)), the speed V₁ of thestacker-conveyor 12 is then reduced by using the spacing 16 as shown inFIG. 3(II) to: ##EQU1## However, in the case of the double-piece cuttingprocess (FIG. 4(III)), when the carrying speed V₁ of thestacker-conveyor 12 is reduced down to V₁ =V₂ ×l/L as shown in FIG.4(II), since the sheet 11" die for the double-cutting process is cut tothe shape in which the foregoing piece and the following piece are leftconnected with each other by the die cutter, it would not be feasible tohave normal cutting operation as these died sheets 11" may come tooverlap one upon the other, and consequently, the carrying speed V₁ ofthe stacker-conveyor 12 is forcibly made V₁ ÷V₂ as shown in FIG. 4(I)(identical with FIG. 3(I)), then resulting in such undesirable problemsthat the leading edges of the died sheet 11" would be damaged by a toolarge shock load when hit against the cardboard stopper 14 in stacking,or the died sheets 11" would be stacked irregularly.

DISCLOSURE OF THE INVENTION

In consideration of the problems noted above, it is an object of thepresent invention to provide an improved conveyor system for planarobjects which can obviate such a possibility of damages to be receivedwhile being stacked or an inconvenience of irregular stacking in thestep following the die-cutting process.

In the conveyor system according to the present invention, there areprovided a detecting device adapted to detect the current end positionof a planar object fed from the preceding step, a delivery memberadapted to deliver the planar object while having it sandwichedtherebetween, and a speed change device adapted to change the deliveryspeed of the delivery member in accordance with the timing of thefollowing step on the basis of the signal from the detecting device, andas the conveying speed of the following stacker-conveyor can be made asslow as V₁ =2 l/L even with the died sheet processed in the double-piececutting operation, there is attained such advantageous effects asavoiding the risk of damaged rendered at the leading edge of a diedsheet or the inconveniences of irregular stacking while being stackedupon the stacker-conveyor in the following step, accordingly.

In addition, there are required only such simple delivery members as twosmall-diametered sandwiching rolls to be driven for the delivery of theprocessed sheets, which would have a relatively small inertia value GD²and therefore require a relatively small capacity driving motor, thuscontributing to the curtailment of cost, and which is proven to beadaptable to the double-sheet cutting operation and so useful in theapplication to the general purpose machine for manufacturing thecorrugated cardboard boxes.

The present invention will now be described taking the reference topreferred embodiments thereof shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 5 is a schematic diagram illustrating the mutual relationship of aseries of planar objects aligned on the delivery to the delivery memberaccording to the present invention;

FIG. 6 is a side elevational view showing a preferred embodiment of theconveyor system for the planar objects according to the presentinvention;

FIG. 7 is an illustrative diagram for depicting the function of theconveyor system;

FIG. 8 is a front elevational view showing the speed change device andparts relative thereto of the conveyor system;

FIG. 9 is a front elevational view showing the same speed change deviceand parts relative thereto by way of another embodiment; and

FIG. 10 is a general side elevational view showing the delivery memberconstruction by way of another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Shown in FIG. 6 are an anvil cylinder 7, a die-cut cylinder 8, a dieelement 9, a sheet delivery conveyor (scrap conveyor) 10, a died sheet(through the double-piece cutting process) 11", a stacker-conveyor 12, acounter-stacker 13, a spacing 16, an photoelectric tube 32, and asandwiching roll section 31, and shown in FIG. 8 are sandwich (rubber)roll elements 34, 34, a bearing 35, gears 36, and a DC (variable speed)motor 37. Also, FIG. 5 is a schematic diagram showing a series of diedsheets ○1 through ○6 before delvered from the sandwich roll elements 34,34, in which L depicts the circumferential length of the die-cutcylinder 8. Also in FIG. 7 there is shown a timing chart showing thechanges of rotating speed of the sandwich roll elements 34, 34. Thesandwich roll elements 34, 34 shown in FIG. 8 are fixed in operativeposition on a single roll shaft 33 disposed with a given gap, and arearranged opposedly to respectively form a pair of rolls in thesandwiching roll section 31. Each of these sandwich roll elements 34 isformed with a layer of soft rubber sheet in its circumference so that itmay not squeeze and crush the corrugated cardboard sheets while passingtherethrough, and also may be worked with slitting. The upper and lowerroll shafts 33 are held rotatably by using the bearings 35 andoperatively in such a manner that the cardboard sheet may be carried ina sandwiching manner by the engagement of the sandwich roll elements 34,34, and on one sides of these roll shafts 33 there are fitted the gears36 meshing with each other at the ratio of 1:1. On the extension of oneend of the roll shaft 33 there is installed a pulley, which is connectedoperatively to another pulley on the DC motor 37 by using a V-shapedbelt or the like; with this arrangement, any change in the rotatingspeed of the sandwich roll elements 34, 34 may be accomplished bydetecting the current edge position of a cardboard sheet to be fed at ornear the central portion of the upper and lower sandwich roll elements34, 34, and by feeding thus-obtained signal into the DC motor 37, andthus changing the rotating speed of the DC motor 37, accordingly.

Next, referring to the operation of the delivery conveyor 10 accordingto FIG. 5 which shows the state before the died cardboard 11' reachesthe sandwich roll elements 34, the sheets ○1 , ○2 ; ○3 , ○4 ; ○5 , ○6depicts respectively the state of sheets fed from the blank cardboardsupply station 1, or in other words the state that these sheets aredisposed in a discrete relationship with each other. The spaces betweenthe sheets ○2 and ○3 , and between ○4 and ○5 represent a difference inthe circumferential length of the die cut cylinder 8 and the overallextension of the died sheets ○1 and ○2 . Δl represents a small gapproduced between each of the adjacent died sheets. The rotating speed(the circumferential speed of the roll surface) V₃ of the sandwich rollelement 34 (or the rotating speed of the DC motor 37), which may beknown by detecting the timing that the edge of the died cardboard 11'passes by using the photoelectric tube 32, is changed as shown in thetiming chart of FIG. 7. FIG. 7 shows the relationship between the timingof detecting the passage of the died cardboard 11' by the photoelectrictube 32 (that is, the case that the gap between the adjacent sheets isdetected is defined to be the light receiving state, while the case thata sheet is detected being defined to be the light blocking state.) andthe current rotating speed of the sandwich roll element 34. The sandwichroll element 34 is driven at the rate V₃ =V₂ while the sheet ○1 passesthe photoelectric tube 32, and then, upon the blocking of thephotoelectric tube 32 by the leading edge of the sheet ○2 , is reduceddown to V₃ =V₁, or the level of 2 l/L×V₂. Thereafter, the photoelectrictube 32 functions to detect the gap between the sheets ○2 and ○3 , andthe sandwich roll element 34 are again driven with an increased speed ofV₃ =V₂. With the repetition of such operation, a series of diedcardboard 11' may be delivered on the stacker-conveyor 12 at a generallyequal interval of Δl' one after another, accordingly. The driving speedof the upper and lower sandwich roll elements 34, 34 is increased orreduced with the same speed rate in proportion to the rotating speed V₂of the die cut cylinder 8.

FIG. 9 shows another embodiment of the invention wherein the rotatingspeed of the sandwich roll element 34 is changed by shifting a firstelectromagnetic clutch 40, etc. incorporated or installed otherwise in amotor 38 and a pulley and a second electromagnetic clutch 41, etc.incorporated or installed otherwise in a second motor 39 and a pulley,with which embodiment there is attainable an equivalent effect andfunction to that of the previous embodiment.

FIG. 10 shows a further embodiment of the invention, wherein thesandwich roll elements and the speed change device are replaced with aconveyor belt 44, a conveyor roll 45 and a motor 42, with which there isalso attainable an equivalent effect and function to that of theembodiment described hereinbefore.

We claim:
 1. A conveyor system including means for changing the spacing between planar objects carried on the conveyor system and which start on the conveyor system in pairs with the spacing between the objects of the pair being small and the spacing between the pairs of objects being large, said spacing changing means comprising:a detecting means for detecting the leading edge of a planar object on said conveyor system and fed from a preceding step, a delivery member positioned along the conveyor system for engaging a planar object of the conveyor system on opposite faces for delivering the engaged object from the conveyor system, a speed change means connected to said delivery member for changing the speed of delivery of said delivery member from a first higher speed during a time from the detection of the passage of a leading edge of a first pair of objects to the detection of the passage of the leading edge of the second object of the said first pair of objects, to a second lower speed of delivery of said delivery member during a time from the detection of the passage of a leading edge of the second object in said first pair of objects to the detection of a leading edge of the pair of objects next succeeding said first pair of objects.
 2. A spacing changing means as claimed in claim 1 in which said second lower speed of delivery is a speed V1 and is according to the expression:

    V1=V2×(2 l/L)

wherein: V2 is the first higher speed of delivery, l is the length of an object in the direction of movement of the conveyor system, and L is the distance in the direction of movement of the conveyor system from the leading edge of a first pair of objects to the leading edge of the next succeeding pair of objects. 